Improvement in trusses for bridges



G. W. OOOLEY. Truss for Bridges.

No. 208,155. l atented S ept. 17.1878

WWW Ne ILFETERS. PHOTO-L'ITHOGRAPHER, WASHINGTON, D16

UNITED STATES PATENT OFFICE GEORGE IV. COOLEY, OF MINNEAPOLIS,MINNESOTA.

IMPROVEMENT IN TRUSSES FOR BRIDGES.

Specificationforming part of Letters Patent N0. 208,155, dated September17, 1878; application filed December 31, 1877.

To all whom it may concern:-

Be it known that I, GEORGE W. CooLEY, of Minneapolis, in the county ofHennepin and State of Minnesota, have invented certain new and usefulImprovements in Trusses for Bridges, &c., of which the following is aspecification:

The object of this invention is the construction of bridge and rooftrusses in such a manner that the strain resulting from a load upon theroadway or top may be communicated directly to the main compressivemember of the truss, and thence by direct thrust to the abutments; andto this end the improvement consists, first, in the combination, in abridge or roof truss, of two oblique shoreward-thrust rafters, havingtheir upper ends notched to rest level upon a centerpost, abottom chord,upon the ends of which the feet of said rafters and center post rest, atop chord, between and resting against which and the upper sides of saidrafters are arranged only shoreward-thrust braces, suspension-rodsconnecting said top and bottom chords, and upright braces arrangedbetween said chords, whereby the entire downward strain upon said trusswill be directed toward its abutments; second, in a compound center postfor bridge and roof trusses, the same consisting of a central memberclamped edgewise between the broad sides of two side posts, having equaldimensions therewith, and connected by bolts outside of the said centralmember.

In the accompanying drawing, Figure 1 represents a side view of one halfof the truss, the other half being identical therewith. Fig. 2 is ahorizontal section of the center post on the line a b, Fig. 1. Fig. 3 isa detail side elevation, showing the connection of the uprights, braces,and suspension-rods with the top chord. Fig. 4 is a detail sideelevation, showing the junction of the lower chord, rafter, upright,

and shore-brace; and Fig. 5 is across-section of the truss at one sideof the center post.

The letter A indicates the lower chord, which extends between the piersor abutments. B is the top chord, composed of the two slightlyinclinedbeams B B. O G are the rafters,

having their lower ends shaped to fit 'seats having approximatelyvertical and horizontal sides, and their upper ends notched so as torest level upon and meet over the top of the center post E.

F indicates the braces between the rafters and the upper chord, B, thesebraces on each side of the center post inclining downwardly toward theshore ends of the truss, and having their ends fitted into notches f inthe rafters and upper chord. F designates the shore-braces, and G theuprights extending. between the upper and lower chords andintermediately bolted to the rafters. H indicates suspension-rodsextending through the rafters and braces, and having screw-threaded endswhich project through the upper an d lower chords and binding-plates hon the outer edges of said chords, and are provided with tightening-nutsh.

Obliquely through the upper chords and transversely through the. upperends of the braces extend bolts g, which serve to hold said bracessnugly in place and prevent them from displacement by shrinkage,warping, 0r jolting. Similar bolts 9 bind the lower ends of the bracesto the rafters.

The center post E is composed of three separate parts, 0 e e, of equaldimensions, and having an oblong cross-section, the center member, 0,being arranged edgewise between broad faces of the side posts 6 e, whichare firmly clamped against it by transverse side posts, but not throughthe central member, 0. The four center suspension-rods t t t t, havingtheir opposite ends secured by nuts and plates on the upper surface ofthe bottom chord, pass between the flanges formed by the members 0 e ofthe center post.

In the foregoing description I have referred to the chords, rafters,braces, and uprights as if they were each laterally-continuous pieces;but they may each be composed of two or more parallel and similar partsor members, and I prefer to construct the chords, rafters, and braceseach of the three parallel members, and the uprights each of twomembers, one of which stands at each side of the central member of achord, brace, or rafter, and between I plicate the suspension-rods, asshown at H H, and locate them between the parallel members of thechords, rafters, and braces, firmly connecting their upper ends to metalplates arranged across the upper edge of the complete top chord andtheir lower ends to similar plates beneath the complete lower chord.

In arranging the oblique braces between the rafters and top chord, Iplace the ends of said braces either in notches cut in the rafter andchord or in suitably-formed head and foot plates properly bolted inplace; and I may use any number of said braces, but I usually have theirnumber equal to the number of uprights and while their tops are attachedto the top chord at the junction therewith of certain of theuprightstheir lower ends rest upon the rafters alongside other uprights closerto the shore end of the truss, so that the bolts which bind the uprightsto the rafters directly assist said rafters in resisting the downwardthrust of the said braces.

The suspension-rods and bolts should, of course, always be made ofmetal; but the other members of the truss may be made of wood or metal,as desired.

The upper ends of the rafters and the abutting ends of the parts B B ofthe top chord are connected bysplice-bracing, as shown in dotted linesat s, Fig. 1. p The shore-panels of the upper chord and theshore-uprights may be omitted, if desired, or retained to secureadditional stiffness in case of a number of spans; and the top chord,when the truss is used for a bridge, may be continuously horizontalinstead of inclining each way, but will be, preferably, inclined whenused for a roof or bridge.

It is obvious that any downward strain upon the center of either chordof the truss will have a tendency to spread the rafters, and thus givethem an endwise thrust against the shoulders at the shore end of thebottom chords, which thrust is resisted by the abutments, which areusually of firm stone-work or other masonry; and it will also be readilyseen that downward strain at any intermediate part of the truss willgive an endwise thrust to the braces, which is communicated to therafters, and through the rafters to the abutments, as before described,so that at whatever point of the truss strain is brought to bear itisthrown shoreward, Where resistance can, with the most facility, beprovided, and the bridge of roof relieved of liability to break down.

What I claim is 1. The combination, in a bridge or roof truss, of twooblique shoreward-thrust rafters, having their upper ends notched torest level upon a center post, a bottom chord, upon the ends of whichthe feet of said rafters and center post rest, a top chord, between andresting against which and the upper sides of said rafters are arrangedonly shoreward-thrust braces, suspension-rods connecting said top andbottom chords, and upright braces arranged between said chords, wherebythe entire downward strain upon said tru'ss will be directed toward itsabutments.

2. The truss center post composed of three parts of approximately equaldimensions, and the outer parts forming flanges connected by bolts forsecuring the center part in place, substantially as described.

In testimony that I claim the foregoing I have hereunto set my hand andseal.

GEO. V. GOOLEY. [L. s]

Witnesses:

L. S. BUFFINGTON, B. W. FIsK.

